Messages in this thread | | | From | Peter Feuerer <> | Subject | Re: [PATCH v3 4/6] acerhdf: Use bang-bang thermal governor | Date | Mon, 12 May 2014 12:27:08 +0200 |
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Hi Javi,
Javi Merino writes:
> Hi Peter, > > On Sat, May 03, 2014 at 06:59:24PM +0100, Peter Feuerer wrote: >> acerhdf has been doing an on-off fan control using hysteresis by >> post-manipulating the outcome of thermal subsystem trip point handling. >> This patch enables acerhdf to use the bang-bang governor, which is >> intended for on-off controlled fans. >> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> CC: Zhang Rui <rui.zhang@intel.com> >> Cc: Andreas Mohr <andi@lisas.de> >> Cc: Borislav Petkov <bp@suse.de> >> Cc: Javi Merino <javi.merino@arm.com> >> Signed-off-by: Peter Feuerer <peter@piie.net> >> --- >> drivers/platform/x86/Kconfig | 2 +- >> drivers/platform/x86/acerhdf.c | 34 +++++++++++++++++++++++++++++----- >> 2 files changed, 30 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig >> index 27df2c5..0c15d89 100644 >> --- a/drivers/platform/x86/Kconfig >> +++ b/drivers/platform/x86/Kconfig >> @@ -38,7 +38,7 @@ config ACER_WMI >> >> config ACERHDF >> tristate "Acer Aspire One temperature and fan driver" >> - depends on THERMAL && ACPI >> + depends on ACPI && THERMAL_GOV_BANG_BANG >> ---help--- >> This is a driver for Acer Aspire One netbooks. It allows to access >> the temperature sensor and to control the fan. >> diff --git a/drivers/platform/x86/acerhdf.c b/drivers/platform/x86/acerhdf.c >> index 176edbd..afaa849 100644 >> --- a/drivers/platform/x86/acerhdf.c >> +++ b/drivers/platform/x86/acerhdf.c >> @@ -50,7 +50,7 @@ >> */ >> #undef START_IN_KERNEL_MODE >> >> -#define DRV_VER "0.5.30" >> +#define DRV_VER "0.5.31" >> >> /* >> * According to the Atom N270 datasheet, >> @@ -259,6 +259,14 @@ static const struct bios_settings_t bios_tbl[] = { >> >> static const struct bios_settings_t *bios_cfg __read_mostly; >> >> +/* >> + * this struct is used to instruct thermal layer to use bang_bang instead of >> + * default governor for acerhdf >> + */ >> +static struct thermal_zone_params acerhdf_zone_params = { >> + .governor_name = "bang_bang", >> +}; >> + >> static int acerhdf_get_temp(int *temp) >> { >> u8 read_temp; >> @@ -440,6 +448,15 @@ static int acerhdf_get_trip_type(struct thermal_zone_device *thermal, int trip, >> return 0; >> } >> >> +static int acerhdf_get_trip_hyst(struct thermal_zone_device *thermal, int trip, >> + unsigned long *temp) >> +{ >> + if (trip == 0) >> + *temp = fanon - fanoff; >> + >> + return 0; >> +} >> + > > I think you should only return 0 if you've updated the temperature. > Otherwise you're telling the calling function that everything went all > right but you may be leaving garbage in *temp. What about > > if (trip != 0) > return -EINVAL; > > *temp = fanon - fanoff; > return 0;
Yes, sounds good. What about trip == 1? This is a valid trip point for acerhdf (critical) and one could argue, that it has a valid hysteresis of 0. - Thus EINVAL would be wrong here.
thanks and kind regards, --peter;
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